Connecting art and engineering in Streicker Bridge critique

Kenneth Liew (right) worked with his advisor, Branko Glišic (left), an assistant professor of civil and environmental engineering, to monitor the structural health of Streicker Bridge, a new pedestrian walkway on the Princeton campus.

By Chris Emery

For his senior thesis project, Kenneth Liew found a bridge that connects his interests in art and engineering.

Combining concepts from architecture, sociology and engineering, Liew assessed whether Streicker Bridge, the new pedestrian walkway arching across Washington Road that will open in the fall, succeeds both as a work of art and as a functional structure. His approach included working with his thesis adviser, Branko Glišic, an assistant professor of civil and environmental engineering, to use cutting-edge sensors to monitor the structural health of the bridge the way a doctor might measure heart rate or blood pressure to assess a patient.

“The bridge is an important piece of structural art, and we can use structural health monitoring to ensure its long-term existence on campus,” said Liew, a civil and environmental engineering major who also earned a certificate in the Program in Architecture and Engineering.

Liew was intrigued when he learned that Streicker Bridge was designed by Christian Menn, an influential Swiss bridge engineer whose work Liew had studied under David Billington, an emeritus Princeton engineering professor. Menn’s bridges blend artistic flair with innovative concrete engineering to assure structural integrity, prompting Billington to label him a “structural artist.”

For his thesis, Liew explored the social importance of the bridge, including its functional and symbolic role connecting various scientific disciplines on campus. The bridge will link Icahn Laboratory, which houses the Lewis-Sigler Institute for Integrative Genomics, and the new Neuroscience and Psychology buildings, all situated on the west side of Washington Road, with the new Chemistry building and Jadwin Hall, home of the Department of Physics, on the east side.

"The bridge’s design, a single span in the middle that splits in two on either end, symbolizes this connection,” Liew said. “But it’s a difficult shape to engineer.”

The bridge is outfitted with some 100 point sensors, together capable of taking about 25,000 measurements per second. Also running through the concrete is a 122-foot-long, cable-like sensor that takes measurements at 800 additional points. “The sensors serve as a kind of nervous system for the structure,” Glišic said. “They tell you when something is wrong.”

Although the sensors measure a range of parameters, Liew’s project focused on tracking the changes in strain and temperature in the concrete to see if they match with the predictions of the designers.

He combined his preliminary physical assessment based on the sensor data with his study of the economic, social and artistic values of the structure, and used these criteria to measure Streicker against similar bridges. “Compared with other bridges, its cost is warranted based on its functional and social value,” he said. “But it’s also exceptionally elegant.”